Most Bluetooth speakers, including the JBL Charge 4, offer off-grid sound via an internal battery. And when that power runs out, you can recharge it via an AC or car adapter. To charge, use a USB 2 charger that delivers 5 volts at 2.3 amps. Such a unit comes with the speaker. But sometimes though, … Continue reading JBL Charge 4 Not Charging — How to Fix